rxpjks1 – It's not the number of figures that determines the level at which a set of rules is pitched; it's the author's design goals, and CLA is flexible in this regard.
Chris Peers claims in his introduction that it's up to you to decide what your units represent: anything from a platoon to a brigade. Some people will hate this approach, and others will value it; I'm in the latter camp. In the 1913 – 1914 Mex Rev campaigns that primarily interest me the battles progressively upsized from battalion, to brigade, to division to corps size. If you want to avoid having to use four different rule sets to represent every level with precise accuracy, and having to amass a collection that can cover them all, it greatly simplifies things; and for me this period is one of third-rate, untrained or poorly trained, improvised, rag-tag armies, and is more about gigantic egos struggling for total dominance against a colourful cultural and geographic background than sophisticated armies with the latest technology engaged in 'scientific' warfare – so I feel comfortable taking a relaxed approach to its tabletop representation.
If you want a more formal large battle rule set you'll have to adapt something designed for WW1, such as Great War Spearhead, or better still, rules for an analogous conflict such as the RCW – so, for instance, Red Actions. If you don't mind playing on a gridded table there's Square Bashing from Peter Pig for divisional level battles with units representing battalions. The 2nd edition army lists book even includes Mex Rev lists, although I don't recall being overly impressed with their historical accuracy.
Just while we're on the subject, when I posted my CLA mods I missed a couple of points:
1. No army can have staff officers except Federales, any army in 1915, and Carranzistas thereafter, which are allowed one.
2. Given his historical tactics I considered denying any army commanded by Pancho Villa the use of the reserves rule, but because his troops will either be irregular or poorly trained there's only a low chance of them turning up if they are held in reserve, so resort to it is effectively discouraged anyway.
If this rules mechanism is at all realistic it offers a logical explanation for Villa's oft-criticised failure to use reserves (who would have thought such an apparently simple game system as CLA could so accurately reflect the historical reality?).
If you want to play Mex rev in 15/18mmm, Darryl, you'll have to adapt and convert. Boers, Old West, and Chinese Warlord figures are the ones to look at.
That's interesting news about Italaeri, Umpapa. Of course we've seen these promises before: Imex has had a set of Villistas 'in the works' for at least a decade… and there's still no sign of it!
WW1 British will only work as Federales if you're very relaxed about historical accuracy: the uniform, webbing, equipment and armament are all wrong.